1. Field of the Invention
This invention pertains to a farm implement, more particularly to a cultivator apparatus which is well adapted to low tillage cultivation of growing crops to minimize weeds. The invention provides a novel field adjustment system to position the cultivator discs for optimum effectiveness.
2. Description of the Related Art
A number of prior patents show a variety of systems for adjusting the position of the individual discs in a planter or cultivator, but none of those show a simple, positive locking and positioning system. For example, Lindstrand U.S. Pat. No. 556,356 shows complementary segmented slots for angular positioning of pivotally mounted standards to a specific angle. Similar angular positioning means is shown for the cultivator discs. The Lindstrand system provides only angular adjustments using a complicated system which requires extensive manufacturing steps, and which could be damaged or broken under typical field conditions.
Rutter U.S. Pat. No. 2,430,434 discloses a U-bolt clamping assembly which requires loosening four nuts to adjust. The radial adjustment has no positive positioning means, and a positioning cam is required to hold the standard in place, making this a complex system which requires loosening four bolts every time an adjustment is desired. The cam does not prevent the standard from slipping away from the cam's face during rough field use.
The disc plow shown in Davis U.S. Pat. No. 2,577,952 shows complementary hubs having intermeshing teeth for making angular adjustment of a disc plow standard. The system appears to be complex and expensive. Davis does not appear to have any means for lateral adjustment of his plow discs.
Williams U.S. Pat. No. 2,829,577 describes a disc plow having a complex adjustment system including a U-bolt clamping means for horizontal adjustment and an angular adjustment plate including a pivot bolt and U-shaped bracket.
Keplinger et al U.S. Pat. No. 3,244,237 describes both vertical and angular adjustment, but no positive position locking means. Instead, the tightening bolt extends through a slot and may be subject to slippage in rough field use conditions.
An independently adjustable disc member is shown in Ernst U.S. Pat. No. 4,009,759, which employs set bolts which are prone to slipping under rugged field conditions. There is no solid locking feature in this patent.
Williams et al U.S. Pat. No. 4,295,532 and David et al U.S. Pat. No. 4,550,122 both show complex adjustment means for trash clearing discs specifically intended for low tillage cultivation. Williams et al adjusts for angle, only, but not for height. David et al only adjusts for height, and doesn't adjust for width , or angle. Williams et al's clamping bolts pass through slots in the disc mounting brackets, and would be subject to slippage under rough field use conditions.
In summary, all of the above patents fail to provide a simple means for easy and exact adjustment of the individual cultivator discs in a cultivator assembly which remains firmly locked in the set position even during rugged field usuage. In low tillage cultivation, there is a special need for rapid and precise adjustment of the discs to meet particular field conditions.